Motorized spindle



Jan. 21, 1969 N. GOTTLIEB 3,422,726

I MOTORIZED SPINDLE Filed June 27, 1966 Sheet of 2 SOURCE 0F 6 0, PRGSSURE FIG. I

INVENTOR NATHAN GOTTLIEB ATTORNEYS 21, 1969 N. GOTTLIEB MOTORIZEDSPINDLE Sheet Filed June 27, 1966 FIG. 8

FIG. 4

FIG. 6

FIG. 7

FIGS

FIG. IO

INVENTOR NATHAN GOTTLIEB ATTORNEYS United States Pate 5 Claims ABSTRACTOF THE DISCLOSURE A motorized spindle consists of a stator having anelliptical chamber formed therein and a cylindrical rotor with adiameter equal to the minor diameter of the stator rotatably supportedwithin the stator on a shaft. The rotor has five vanes slidablysupported in radial slots. The stator includes surfaces which abut thesides of the rotor and communicate pressurized air to the rotor atcertain angular positions thereof. The pressurized air urges the vanesoutwardly and pressurizes chambers formed between the elliptical statorsurface and the rotor, and bounded by the vanes. A pair of sinks toatmosphere are disposed at diametrically opposed points on the stator.The spacial relationship of the fluid chambers, vanes and sinks is suchthat working chambers are pressurized until they make fluid connectionwith the sink. The shaft is supported on bearings disposed adjacent toboth faces of the rotor so as to provide a spindle.

This invention relates to a compact motorized spindle and moreparticularly to a spindle powered by a fluid motor having radiallymoving vanes.

A major problem associated with the working accuracy of grindingmachines relates to the tools used in dressing or trueing the grindingWheel. Conventionally the means for dressing the grinding wheelcomprises a single or cluster point diamond tool which periodicallytraverses the working surface of the grinding wheel. Tools of this typerequire frequent rotation and replacement due to rapid wear. Replacementof conventional dressing tools of this type presents a problem becauseof the costly downtime of the grinding machine. Therefore, there hasbeen a demand for a dressing tool for such grinders which is durable,has a longer life than conventional single point or cluster type diamondtools, provides a better dressing, and which is capable of dressing andtrueing the grinding wheel at a faster rate.

One effort in the prior art to provide a tool to satisfy therequirements for an improved dressing tool takes the form of a circulardiamond impregnated dressing wheel mounted on a spindle and powered forrotary movement by a fluid motor of the turbine type. This effort toprovide an improved dressing wheel has been only partially successful. Aturbine powered spindle has severe limitations in that the turbine mustbe operated at a high rotational speed thus requiring a reduction gearto reduce the output to a speed corresponding to an eflicient dressingwheel speed. The combination of turbine motor, reduction gear andspindle produces a device having a length requiring extensivemodification to existing grindersfor the purpose of installation.

The present invention obviates the problems encountered in the prior artin providing an improved dressing wheel for grinding machines whichtakes the form of a motorized spindle which has utility not only inproviding rotary power for a dressing wheel, but is also useful as asource of compact rotary power for a wide variety of tools. Thepreferred embodiment of the present invention, which will subsequentlybe described in detail, takes the form of a shaft journaled in a pair ofspaced bearings suitably chosen to support the shaft for radial andthrust ice loads imposed on a tool carried by one end of the shaft. Thebearings and the shaft carried therebetween are mounted in a housingdefining a chamber having a generally elliptical cross-section includinga narrow diameter and a large diameter. The shaft has an enlargedcircular section disposed in the chamber and provided with a circulardiameter corresponding to the narrow diameter of the chamber. Theenlarged section of the shaft which will hereafter be referred to as arotor is concentric with the axis of symmetry of the chamber so that apair of diametrically opposed crescent shaped working chambers areformed with respect to the rotor.

The rotor preferably has an odd number of equiangularly spaced slotsformed radially inwardly from its circumferenttial surface and which runthe length of the rotor section. A vane is slidably disposed in each ofthe slots with a length corresponding to the length of the slot and aheight less than the depth of the slot. A pair of arcuate fluid inletports are provided in the housing, each of which is associated with aworking chamber. As the rotor rotates to bring a slot into registry withone of the crescent shaped working chambers, the inlet port deliverspressurized fluid, preferably compressed air, to the bottom of the slotand behind the vane to urge the vane into an extended position whereinits free edge moves into a fluid-tight sliding relationship with theouter surface of the working chamber.

A passage is associated with each of the slots and has one extreme endformed in the periphery of the rotor on the side of the slot oppositethe direction of rotation of the rotor and an opposite extreme endcommunicating with the bottom of the slot. The vane is urged into anextended position by the pressurized fluid at the commencement of itspower stroke. The pressurized fluid is then delivered through thepascage and behind the extended vane to impose a working force againstthe surface of the extended vane, causing the vane to impart a rotarymotion to the rotor. The vane traverses the crescent shaped workingchamber to terminate its power stroke by registering with an exhaustport provided in the housing. As the working vane registers with theexhaust port of the working chamber, the slot of the vane moves out ofcommunication with the inlet port so that the vane floats in its slotuntil it registers with the opposite working chamber where the cycle isrepeated. Since there are two working chambers and preferably fiveequiangular spaced working vanes, there are always two vanesoverlappingly progressing their power strokes one in each of theopposite chambers.

The motorized spindle embodying the present invention achieves a muchsmoother and vibration-free operation than has heretofore been availablein motorized spindles by employing two working vanes in diametricallyopposite working chambers, thereby balancing the radial forces imposedon the spindle. Furthermore, by employing two blades in simultaneousworking engagement, greater torque is available at the tool than hasheretofore been available as compared to the output from conventionalfluid rotary motors of comparable size. When utilized as a power sourcefor a dressing wheel in a centerless grinder the improved motorizedspindle achieves a better dressing of the grinding wheel because of itsgenerally vibration free characteristics.

Another feature of the improved powered spindle lies in its compactconfiguration. The inherently long configuration required in turbinepower spindles is eliminated in the preferred spindle embodying thepresent invention in that the fluid vane type motor operatessatisfactorily at a rotational speed cor-responding to the desiredrotational speed of the dressing wheel thus eliminating the requirementfor a reduction gear connection. Because of this more compactconfiguration, the preferred powered spindle can be incorporated inpresent conventional grinding machines without requiring costly and timeconsuming modifications to the frame of the grinders. An example of thegreatly reduced size for a given power output is illustrated in thedressing wheel application where more rotary power is available to thewheel for the same power input in a unit having an overall length offour inches than is available from a conventional turbine type unitrequiring an overall length of 8-10 inches.

It is to be understood that the utility of the present invention is notlimited to dressing Wheels, but that the free end of the spindle can beadapted to carry a drill head or other tool requiring a source of rotarymovement.

A still further advantage of the improved fluid vane type motor is thatthe total horse-power of the spindle can be increased without increasingthe overall diameter of the tool; thus it has been found that anadditional one-quarter horse-power can be achieved by adding a module ofone and a half inches of length or less to the rotary motor oralternatively by stacking a plurality of rotors. Because of its compactsize, a handle can be incorporated with the preferred motorized spindleto develop a small durable hand carried drill of screwdriver.

It is therefore an object of the present invention to reduce the size ofmotorized spindles by providing a spindle of this type supported forrotation between a pair of spaced spindle bearings and providing a fluidmotor between the two spindle bearings so that only one set of bearingsis required for the spindle and the motor.

Another object of the present invention is to provide a motorizedspindle having vibration-free characteristics by providing a spindle ofthis type forming an integral component of a fluid vane type motor andhaving a rotor forming an enlarged section of the spindle shaft anddisposed in a motor housing defining a pair of diametrically opposedworking chambers and wherein the rotor has a plurality of equiangularlyspaced guide slots formed therein, a vane associated with each of theslots and adapted for movement between a retracted position within theslot and an extended .position into the working chambers and including asource of pressurized fluid operative to impose a force on the surfaceof the extended vanes to cause the vanes to impart rotary motion to thespindle shaft and where at least one vane is devloping a power stroke ineach of the working chambers at all times so that the forces of thepower strokes are substantially equalized.

It is another object of the present invention to eliminate a dead pointposition in fluid vane-type motors by providing such a motor having apair of oppositely disposed working chambers and a concentric rotorhaving an odd number of working vanes which move into and out ofregistry with the working chambers and wherein at least one vane is atall times extended in its power stroke in each of the chambers butbecause of the odd number of vanes there are never two vanes in theirpower stroke at exactly diametrically opposed positions.

Still other objects and advantages of the present invention will be madeapparent from the following detailed description of a preferredembodiment of invention. The description makes reference to theaccompanying drawings in which:

FIG. 1 is an end view of a motorized spindle carrying a dressing wheelwhich illustrates a preferred embodiment of the present invention;

FIG. 2 is a sectional view of the line 2-2 of FIG. 1;

FIG. 3 is an enlarged sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is an elevational view of the housing sections with the movingparts removed for purposes of describing the porting configuration;

FIG. 5 is a view taken along line 5-5 of FIG. 4;

FIG. 6 is a view taken along line 6-6 of FIG. 5;

FIG. 7 is a view taken along line 77 of FIG. 5';

FIG. 8 is a view taken along line 8-8 of FIG. 5;

FIG. 9 is a sectional view taken along line 9--9 of FIG. 7; and

FIG. 10 is a sectional view taken along line 10-10 of FIG. 8.

Now refering to the drawings, FIG. 2 illustrates a preferred motorizedspindle as comprising a front housing 10 at one end of which is secureda rotor housing 12 and a cap member 14 preferably by a plurality ofbolts 15. A shaft 16 extends longitudinally through the housing 10 andthe rotor housing 12 and has a narrowed end 18 journaled for rotation ina needle bearing 20 seated in a recess in the cap 14. The shaft 16 hasan enlarged portion 22 near its mid-section which is journaled forrotation in a bearing 24 seated in the housing 10. The bearing 24 ispreferably of the double row angular contact ball bearing type capableof supporting the shaft 16 for both radial and thrust loads imposed onthe free end. The inner race of the bearing 24 is held in place by aretainer ring 26 and a spacer 28, both of which are carried by the shaft16. The outer race of the bearing 24 is held in place by a shoulder 30and a spacer 32 which is positioned by a retaining ring 34 seated in thehousing 10. The spacer 32, in addition to retaining the outer race ofthe bearing in position, defines an annular shoulder for housing a shaftseal 36. Normally upon installation, the bearing 24 is fitted to theshaft which is then inserted in the housing 10 and a suitable lubricantprovided for the bearing which is retained in the housing in lubricatingcontact with the bearing by the seal 36. The extending end of the shaft16 carries a dressing wheel 38 which is preferably fixed to the shaft 16against relative rotation by a key 40. An annular retaining ring 42 issecured to the outer end of the shaft and prevents axial displacement ofthe dressing wheel with respect to the shaft 16.

The dressing wheel 38 is preferably of the diamond impregnated type. Itis to be understood that although the prefered embodiment of theinvention takes the form of a device for imparting rotary motion to adressing wheel, that the preferred motorized spindle can accommodate acircular grinding wheel, a drill head, or other tools of the typerequiring rotory motion without departing from the scope of the presentinvention.

Still referring to FIG. 2, the housing 10 is adapted to accommodate asuitable supporting apparatus having a hollow nut (not shown), and whichis connected to the housing 10 by means of the threaded bore 44. Thesupporting device delivers a cooling lubricant to the dressing wheel 38through a passage 46, formed in the housing 10 and which has an outletadjacent the circumferential surface of the dressing wheel 38.

An annular rotor section 48 is keyed to the shaft 16 and disposed in achamber 50 provided in the rotor housing 12. The rotor section 48 has acircular periphery and the chamber 50 preferably has an ellipticalcross-section as can best be seen in FIG. 3. The chamber 50 has a narrowdiameter at a perpendicular relationship with a large diameter. Therotor 48 has a diameter corresponding to the narrow diameter of thechamber 50 and is concentrically disposed therein to form a pair ofsimilar, crescent shaped diametrically opposed Working chambers 52,having exhaust ports 53. The rotor 48 has a length corresponding to thelength of the working chambers.

The rotor 48 is provided with an odd number of longitudinal slots 54which are circumferentially spaced inwardly from the outer surface ofthe rotor 48. A close fitting vane member 56 is slidably disposed ineach of the slots 54 and has a length corresponding to the length of theslot. Each of the vanes 56 has a height less than the depth of the slot54 so that the vanes are free to float therein.

A pair of opposed elongated arcuate inlet ports 58 is associated witheach of the working chambers 52 and are formed in the housing 10 and thecap 14 and radially spaced inwardly from the chambers 52 a distancecorresponding to the depth of the slots 54. A source of pressurized air60 is connected through a hose 61 to a passage 62 formed in end cap 14and which, as can best be seen in FIGS. 8 and communicates with one ofthe ports 58.

The passage 62 communicates with a longitudinal passage 66 in cap 14which is aligned with a longitudinal passage 68 provided in rotorhousing 12. Passage 62 is fluidly connected to a short longitudinalpassage 70 formed in front housing 10 and which, as can best be seen inFIG. 5 communicates with a transversely formed passage 72 and an arcuateslot 74. Passage 72 delivers pressurized air to one inlet port 54 andhas its outer end sealed by a plug 76. The arcuate slot 74 curves aroundas shown so that it can be fluidly connected to the opposite inlet port54 by a passage 78. The outer end of passage 78 is sealed by a plug 80.

Now referring to FIGURES 8, 9 and 10 for a description of the exhaustporting, a short longitudinal passage 81 fluidly connects one of theexhaust ports 53 with an elongated arcuate slot 82 formed in end cap 14.Slot 82 curves around to register with a second longitudinal exhaustpassage 84 which fluidly registers with the opposite exhaust port 53 andregisters in front housing 10 with a passage 86. The exhaust air fromboth of the working chambers is exhausted through passage 86 to anexhaust hose 88. Preferably, a passage (not shown) is fluidly connectedto passage 86 and bleeds suflicient exhaust air to cool bearings 24.

In operation, the compressed air is delivered to the inlet ports 58.Referring to FIG. 3, as the rotor 48 rotates, the slots 54 alternativelymove into and out of registry with the working chambers 52. As slots 54rotate into registry with a working chamber 52, the bottom end of theslot moves into alignment with the inlet port 58 so that the pressurizedair is delivered into the slot and behind the vane 56. The outer edge ofthe vane 56 is forced outwardly against the enlarged surface of theworking chamber 52. Preferably the vanes 56 are formed of a materialsuitable to form a fluid tight seal with the outer surface of theworking chambers such as a fiber like graphite or plastic material. Thepressurized air simultaneous with forcing the vane 56 into its extendedposition is also delivered through passages 66 into working chamber 52and behind the extended vane to impose a force on the extended surfacethereof and thus commence a power stroke. As the vane 56 rotates underthe force of the pressurized air, it continues to extend to accommodatethe enlarged radial surface of the working chamber and then begins toretract within the slot 54 as the radial surface is reduced. The vane 56continues on its power stroke until its rearward surface registers withthe exhaust port 53 thereby exhausting the pressurized air formed in thevolume behind the vane 56 and the adjacent vane. Just before the vane 56registers with the exhaust port 53 it passes out of the registrationwith the inlet port 58 and is generally free to float within its slotuntil it registers with the opposite working chamber 52.

It will be seen that as a result of utilizing a pair of diametricallyopposed Working chambers and an odd number of vanes, there is always aworking vane generating a power stroke in each of the working chambers52. Thus, there are at all times two working vanes which enable thepreferred power or motorized spindle to have greater power output thanconventional fluid vane type rotary motors characterized by a singleworking chamber accommodating a single working vane. It will further beseen that by providing diametrically opposed working chambers which aresimultaneously associated with a power stroke that the forces imposed onthe motorized spindle by the power stroke are substantially balanced tothereby provide a substantially vibration-free device.

Another major feature of the preferred spindle is that by providing anodd number of vanes, which are circumferentially spaced, the preferredmotorized spindle has two vanes overlappingly progressing through theirpower strokes in diametrically opposed chambers, there is no possibilityof a dead point position, that is, a position where all the forces onthe vanes balance each other resulting in a zero net torque. The majorfeature of the preferred motorized spindle lies in the compact designresulting from the spindle and the motor utilizing a common pair ofbearings as distinguished from those types of motorized spindles whereinthe spindle has its own unique set of bearing and the motor associatedtherewith has its own set of bearings thereby necessitating aninherently larger configuration.

This compactness in structure is obtained, in part, by incorporating amotor between that portion of the spindle that is supported between asingle pair of bearings and which normally occupies unused space. Thepreferred embodiment of my invention requires a single pair of bearingsto support the spindle for the rotating forces imposed by the motor andthe load imposed on the tool carried by the spindle.

It is to be understood that although we have described but one preferredembodiment of the present invention that many modifications andrevisions may be made therein without departing from the spirit of theinvention or the scope of the appended claims.

I claim:

1. A motorized spindle, comprising, in combination:

(a) a housing having an elliptical chamber defined therein, said chamberhaving a major axis and a normally extending minor axis;

(b) a shaft supported for rotation in said housing about an axisextending normally to the major and minor axes of the chamber;

(c) an enlarged annular section formed on said shaft and disposed insaid chamber, said annular section having a diameter generallycorresponding to the dimension of said chamber across its minor axis;

(d) an odd number of radial slots, greater than one,

disposed at regular angular intervals about the annular section;

(e) vanes disposed in each of said slots and supported therein formovement between a retracted position wherein their radially outer endsare located in registry with the perimeter of the annular section, andan extended position wherein their radially outer ends extend beyond theperimeter of the annular section;

(f) an even number of means for injecting fluid under pressure into thecavities defined by an extending section of a vane, an adjacent surfaceof the annular section, and a section of the elliptical chamber, duringa particular angle of rotation of said annular section, said means beingdisposed at equal angular intervals about said elliptical chamber, saidfluid urging said vanes into the extended position from said slots sothat the surfaces of said vanes move in fluid sealing contact with thesurface of said chamber; and

(g) an even number of fluid sinks disposed at equal angular intervalsabout the elliptical chamber, and each being positioned so as to contacta cavity defined by an extending surface of a vane, the contiguoussection of said annular member, and a section of said ellipticalchamber, at a point of rotation of said annular member immediatelyfollowing the termination of supply of pressured fluid to said cavity.

2. The motorized spindle of claim 1, wherein five vanes are regularlyspaced about the annular section, two regularly spaced means forinjecting fluid are associated with the annular section and two fluidsinks are associated with the elliptical chamber.

3. The motorized spindle of claim 1, wherein the means for injectingfluid constitute arcuate slots formed in sections abutting said annularsection and spaced longitudinally thereof.

4. The motorized spindle of claim 1, wherein shoulders are formedbetween the sides of the annular section and the shaft and the means forinjecting fluid are contained within sections abutting the annularsection at such shoulders and are arranged to communicate with passagesin said annular section at particular positions of rotation of theannular section.

5. The motorized spindle of claim 4 wherein the shaft is supported by afirst bearing retained in one section abutting one shoulder of saidannular section and a second bearing formed in a section abutting theother side of said annular section.

References Cited UNITED STATES PATENTS 2,222,689 11/1940 Schott 9l119 XJune 91-136 Hauer 91138 X Price 91-138 X Klessig 91138 X MARTIN P.SCHWADRON, Primary Examiner.

IRWIN CHARLES COHEN, Assistant Examiner.

U.S. Cl. X.R.

